Computer input devices using a roller such as mice or keyboards are known in the art. U.S. Pat. No. 6,700,564 B2 assigned to Microsoft Co. and U.S. patent publication No. 2003/0025673 A1 disclose an input device which has a roller to allow users to turn the roller with fingers to change pages, scroll text or edit text of documents during browsing the documents on a computer screen. It is especially convenient for the users to browse the documents, search Web pages or zoom/shrink images and skip pages or lines without striking the page down/up keys on the keyboard, or maneuvering the scroll bar on the browsing window through a mouse.
However the conventional roller device is complicated and bulky. Fabrication and assembly are difficult. Manufacturing cost is higher. To shrink the size of electronic products equipped with such a roller input device also is not easy.